Facebook sent the man a CD with 1,200 pages of data, including his chat conversations, everyone he had ever "poked," events he had been invited to (regardless of whether he attended) and even the IP addresses of the computers he used to log into his account.

The data included information that the consumer thought he had deleted, such as personal messages and people he had "defriended."

"We are concerned that although the user was under the impression that this information was deleted at the user's request, Facebook continued to retain the information," the lawmakers wrote.

They asked Zuckerberg to describe "all personally identifiable information that Facebook collects," how it stores user information and whether it deletes information when a user requests it. They also asked how Facebook balances user privacy with free-speech rights.

"We care deeply about respecting the expectations of the people who trust Facebook with their information and believe that our sound data policies and secure practices are part of the reason people enjoy using our service," a Facebook spokesman said. "We look forward to discussing this in more detail with members of the Bipartisan Privacy Caucus and answering any questions they may have."

The lawmakers, who are all members of the Congressional Bipartisan Privacy Caucus, requested a response to their questions by Nov. 21.